An Air-Cored PM Generator for Renewable-Energy Applications

E Spooner       University of Durham &  Evolving Generation Ltd,     UK

Evolving Generation Ltd, Studio One, Crook Business Centre, New Rd, Crook

Co Durham.  DL 15  8QX,  UK,      Tel. **44 1388 766715,  Fax   **44 1388  766470,

Email   ed.spooner@evolving-generation.co.uk

ABSTRACT

A new form of direct-drive generator for wind turbines is described. It uses permanent magnet excitation and large diameter spoked wheels for the rotor and stator. The usual laminated iron core is absent so there is no attraction between rotor and stator causing distortion and risking airgap closure. Rare earth permanent magnets provide adequate working flux in the ironless magnet circuit. The stator winding consists of separate coils that permit the use of a modular multilevel power electronic converter delivering high voltage. The result is a very lightweight machine that has very low maintenance demands and with a high degree of fault tolerance. The electrical parts are exposed to the elements and the insulation system needs a new approach.